[Ravikiran G Thirumalai - Tue, Aug 25, 2009 at 12:20:55PM -0700]| On Tue, Aug 25, 2009 at 10:31:30PM +0400, Cyrill Gorcunov wrote:| >[Ingo Molnar - Tue, Aug 25, 2009 at 08:15:00PM +0200]| >| | >| >I'm definitely not APIC expert but since I was partially involved| >letme turn in.| >| >Original commit which causes problem for vSMP seems to be due| >to cpu_has_apic bit turned off (ie due to being manually disabled| >or acpi table broken) so further read apic id will return plain| >zero (we're talking about 64 bits now). So frnakly I don't understand| >what is wrong with Ravikiran's patch. In case of apic disabled| >initial apic value will be used anyway (which is latched but| >actually may be changed, but it's not our case).| >| | Exactly my thinking. I hoped the patch I posted solves both cases --| does not depend on local apic id for the "fix crash on certain UP configs"| case in the commit here:| | http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2759c3287de27266e06f1f4e82cbd2d65f6a044c| | And fixes vsmp too.| | >Or perhaps there is an issue in srat numa nodes numbering?| >| | Don't think so, local apic id has been used for for 'flat' and 'cluster'| apic (which was used prior to 'flat') for atleast 15 major releases.| | Cyrill/Yinghai, can you test and confirm if the patch attached does not| regress the 'UP crash case' mentioned in| commit 2759c3287de27266e06f1f4e82cbd2d65f6a044c please?| | ---|

I would like to but I can;t. I don;t even know where were we hangingat this crash case. I was only reading commit changelog and sinceit was said about "not apic bit set" I thought about disabled apic case.

Personally I like much more quirk Yinghai posted which leaves phys id function_bared_ and simple as it should be :)

And since it's too late before kernel release -- introducing read apic backseems to be dangerous I suppose: there are a number of configs which couldbe having side effect. At moment they are tested _with_ Yinghai patch andonly vSMP is issued. Though the problem need to be investigated moreclosely. But I'm not knowing that much in this area.